Dynamic Left Ventricular Outflow Tract Obstruction Research Articles

Silent Threats of the Heart: A Case Series and Narrative Review on Suicide Left Ventricle Post-Aortic Valve Replacement in Patients with Dynamic LVOT Obstruction and Aortic Stenosis.

Aortic stenosis (AS) is the most prevalent valvular heart disease in Europe and North America, with transcatheter aortic valve implantation (TAVI) revolutionizing its management. Hypertrophic left ventricle (HLV) frequently coexists with AS, complicating treatment due to the associated risk of left ventricular outflow tract (LVOT) obstruction, heart failure, and sudden death. A rare but severe post-aortic valve replacement (AVR) complication, termed "suicide left ventricle" (SLV), has emerged, necessitating further study. This report synthesizes current literature on SLV, its pathophysiology, and management strategies, alongside four patient case studies. The patients aged 79-87 years, underwent AVR for symptomatic AS with HLV. Post-AVR, all experienced severe complications, including dynamicLVOT gradients, systolic anterior motion (SAM) of the mitral valve, and severe hypotension, leading to death in two cases. One patient survived following surgical aortic valve replacement (SAVR) with surgical myectomy. One patient survived after TAVI. These cases highlight the critical importance of multidisciplinary Heart Team evaluations and personalized treatment plans in managing SLV. Despite advancements in AVR, SLV remains a complex, life-threatening condition, requiring an exhaustive and multifaceted approach for optimal patient outcomes. This report offers valuable insights into SLV occurrence and management from a clinical perspective.

Abstract 16019: Right Hemidiaphragm Paralysis Leading to Right Heart Failure

Background Diaphragmatic paralysis occurs due to direct or indirect damage to the phrenic nerve and can cause unilateral elevation. Diaphragmatic paralysis is usually asymptomatic; however, we present a case of syncope caused by right hemidiaphragm paralysis leading to extrinsic compression of the right heart causing hemodynamic compromise. Case A 78-year-old female with a history of advanced dementia, and hypertension presented following a syncopal episode and was found altered and hypotensive. A chest X ray showed an elevated right hemidiaphragm. A Transthoracic echocardiogram demonstrated hyperdynamic systolic function of the left ventricle with an ejection fraction of 70 to 75% and a left ventricular outflow tract (LVOT) gradient of 64 mmHg. It was suspected that extrinsic compression of the right atrium and ventricle lead to underfilling of the left ventricle causing LVOT obstruction resulting in hypotension and syncope. Discussion . Due to the patient’s underlying severe dementia her family wished for a conservative approach and additional cardiac investigation was deferred. She was treated conservatively with beta blockers to increase her diastolic filling time and intravenous fluids to promote LV filling in order to reduce her LVOT obstruction. Treatment of diaphragm paralysis depends on the severity of symptoms such as dyspnea on exertion, fatigue and syncope. An option that was discussed was diaphragmatic plication to decrease the intrathoracic pressure and the extrinsic compression on the right heart. More commonly, unilateral diaphragmatic paralysis is asymptomatic and is managed conservatively with observation. Conclusion: Cardiac complications of hemidiaphragm paralysis are rare but this case illustrates how extrinsic compression of the right heart can lead to dynamic LVOT obstruction and highlights the importance of integrating imaging findings when evaluating patients for syncope.

Left ventricular outflow tract obstruction in patients with Ebstein anomaly

ObjectiveIn this study, we investigated the clinical characteristics of patients with Ebstein anomaly and left ventricular outflow tract (LVOT) obstruction as well as possible mechanisms of obstruction as assessed by 2-dimensional echocardiography. MethodsWe queried our institutional echocardiography and surgical databases for patients with the diagnosis of Ebstein anomaly seen from 1985 through 2022. Fourteen patients had the additional diagnosis of LVOT obstruction identified from transthoracic echocardiography. ResultsThe mean age of the 14 patients at the time that LVOT obstruction was identified was 51.9 ± 9.9 years, and 11 (78%) were female. LVOT obstruction (mean gradient 61.0 ± 25.7 mm Hg) was documented at the time of initial diagnosis of Ebstein anomaly for 8, and in the remaining, was recognized on follow-up imaging. Dynamic LVOT obstruction with systolic anterior motion (SAM) was the most common mechanism and was mostly accompanied by leftward septal movement and septal hypertrophy. Seven of the 9 patients with SAM had the diagnosis of hypertrophic cardiomyopathy. Leftward bowing of the septum appeared to be the sole cause of LVOT obstruction in 3 and a contributing factor to SAM in 4. Among the 13 patients who underwent an operation for Ebstein anomaly, 7 had concomitant septal myectomy and 3 had a subsequent procedure. ConclusionsThere are multiple mechanisms of LVOT obstruction in patients with Ebstein anomaly, including SAM and leftward bowing of the interventricular septum, which may exist alone or in combination. Septal myectomy at the time of tricuspid valvuloplasty is safe and effectively reduces gradients in the outflow tract and may prevent the need for subsequent reintervention.

Xenografts Show Signs of Concentric Hypertrophy and Dynamic Left Ventricular Outflow Tract Obstruction After Orthotopic Pig-to-baboon Heart Transplantation.

Orthotopic cardiac xenotransplantation has seen substantial advancement in the last years and the initiation of a clinical pilot study is close. However, donor organ overgrowth has been a major hurdle for preclinical experiments, resulting in loss of function and the decease of the recipient. A better understanding of the pathogenesis of organ overgrowth after xenotransplantation is necessary before clinical application. Hearts from genetically modified ( GGTA1-KO , hCD46/hTBM transgenic) juvenile pigs were orthotopically transplanted into male baboons. Group I (control, n = 3) received immunosuppression based on costimulation blockade, group II (growth inhibition, n = 9) was additionally treated with mechanistic target of rapamycin inhibitor, antihypertensive medication, and fast corticoid tapering. Thyroid hormones and insulin-like growth factor 1 were measured before transplantation and before euthanasia, left ventricular (LV) growth was assessed by echocardiography, and hemodynamic data were recorded via a wireless implant. Insulin-like growth factor 1 was higher in baboons than in donor piglets but dropped to porcine levels at the end of the experiments in group I. LV mass increase was 10-fold faster in group I than in group II. This increase was caused by nonphysiological LV wall enlargement. Additionally, pressure gradients between LV and the ascending aorta developed, and signs of dynamic left ventricular outflow tract (LVOT) obstruction appeared. After orthotopic xenotransplantation in baboon recipients, untreated porcine hearts showed rapidly progressing concentric hypertrophy with dynamic LVOT obstruction, mimicking hypertrophic obstructive cardiomyopathy in humans. Antihypertensive and antiproliferative drugs reduced growth rate and inhibited LVOT obstruction, thereby preventing loss of function.

Comparative study of myocardial function in cases of feline hypertrophic cardiomyopathy with and without dynamic left-ventricular outflow-tract obstruction.

In recent years, hypertrophic cardiomyopathy (HCM) in cats has become much more common in clinical practice due to improvements in diagnostic techniques and equipment performance. One phenotype is obstructive HCM with left ventricular (LV) outflow tract obstruction (DLVOTO). It has been reported that the presence or absence of DLVOTO does not affect long-term prognosis in cats with HCM. In this study, we evaluated and compared myocardial function in HCM-affected cats with and without DLVOTO using the two-dimensional speckle-tracking echocardiography. LV longitudinal strain of the endocardial, epicardial, and whole layer and LV circumferential strain of the epicardium were significantly decreased in all HCM-affected cats compared to healthy cats. However, these values were not significantly different between those with and without DLVOTO. In contrast, the endocardial and whole layers of LV circumferential strain were only significantly decreased in HCM-affected cats with DLVOTO compared to healthy cats. This could be attributed to the fact that the LV pressure load associated with DLVOTO affected the endocardial myocardium more in the LV endocardial layer, and that lower values of LV endocardial strain lowered the values of LV strain in the whole layer. In conclusion, our results suggest that LV myocardial function may have been more compromised in the HCM-affected cats with DLVOTO.

Systolic Anterior Motion of the Mitral Valve in the Presence of Annular Calcification

Mitral annular calcification (MAC) has been reported as a possible cause of systolic anterior motion (SAM) of the mitral valve and dynamic left ventricular outflow tract (LVOT) obstruction. While morphologic features predisposing to SAM in other clinical settings have been described, patients with MAC+SAM have not been systematically investigated. We hypothesized that bulky calcium deposits in the mitral annulus could displace the valve toward the septum, thus promoting development of SAM. We studied 30 patients with severe MAC who had SAM with septal contact. Three comparator groups (matched for age and sex) were developed: 30 controls without MAC or SAM, 30 with severe MAC but no SAM, and 30 with SAM but no MAC. Significant differences were found across groups for mitral valve coaptation point-septal distance (CSD), anterior mitral leaflet (AML) length, left ventricular diastolic dimension, and ejection fraction. Comparing all MAC subjects (n=60) with controls, CSD was less (20.5±4.1 vs 23.2±3.7mm, P=.003) and ejection fraction was higher (67.7%±7.8% vs 60.9%±6.4%, P<.0001) in MAC patients. Within MAC subjects AML was longer (21.9±3.0 vs 17.4±2.2mm, P<.0001) and CSD was smaller (18.0±2.7 vs 23.1±3.6mm, P<.0001) when SAM was present despite similar height of the calcium bar in the 2 MAC groups (12.4±2.9 vs 11.1±3.1mm, P=.11). Regression analysis confirmed AML length and CSD as independent predictors of SAM. MAC+SAM patients also had more echocardiographic risk factors for SAM (acute aortomitral angle, small LVOT, long AML, small CSD, and presence of a septal bump) than MAC/no-SAM patients (3.4±0.9 vs 1.8±1.0, P<.0001). Bulky MAC appears to contribute to dynamic LVOT obstruction when it accumulates in such a way that the mitral valve is displaced anteriorly toward the septum. However, other features are also associated with SAM in these patients, particularly a long AML. A combination of morphologic features and favorable hemodynamics may be needed for SAM to develop in patients with severe MAC.

Prevalence and Prognosis of Atenolol-Responsive Systolic Anterior Motion of the Septal Mitral Valve Leaflet in Young Cats with Severe Dynamic Left Ventricular Outflow Tract Obstruction.

Severe dynamic left ventricular outflow tract obstruction (DLVOTO) secondary to the systolic anterior motion of the septal mitral valve leaflet (SAM) can result either from congenital mitral valve disorders or left ventricular concentric hypertrophy of any cause, in cats commonly hypertrophic cardiomyopathy (HCM). Though HCM cannot be reversed, the question remains whether atenolol can cure cats with severe DLVOTO resulting from a presumed mitral valve dysplasia. In this retrospective case series, client-owned asymptomatic cats younger than 1.5 years with echocardiographic evidence of SAM and severe DLVOTO were included. Oral atenolol therapy and recheck echocardiography after 2-3 months were recommended. The owners and referring veterinarians were called for long-term follow-up information. Of the 28 included cats, 23 were treated with atenolol. Recheck echocardiography performed in 17 cats showed a resolution of SAM in 47%. In the long term, SAM remained absent in only 9% of the treated cats. Cardiac-related death occurred in 26% of the atenolol-treated cats. The long term benefit of twice-daily atenolol therapy was documented in 9% of cats. Whether the cats where atenolol failed to resolve DLVOTO on long-term had HCM, or a therapy-resistant congenital primary mitral valve disorder remains unclear.

Quantification of systolic anterior motion of the mitral valve to predict left ventricular outflow tract obstruction in patients with hypertrophic cardiomyopathy

Abstract Background In patients with hypertrophic cardiomyopathy (HCM), left ventricular outflow tract obstruction (LVOTO) is associated with an increased risk of heart failure and death (1). It is typically caused by dynamic systolic anterior motion (SAM) of the mitral valve leaflet. SAM can be categorized by echocardiography but diagnostic accuracy is limited by high inter-observer variability. Purpose To investigate the accuracy of echocardiographic parameters quantifying systolic motion of the mitral valve leaflets to identify LVOTO in patients with HCM. Methods We present a cross-sectional analysis of the HyperCard Registry, a prospective single-center cohort study enrolling consecutive patients with suspected or confirmed HCM. For the present analysis, patients with confirmed HCM and a valid standardized transthoracic echocardiographic were included. LVOT gradients were measured at rest and during Valsalva maneuver using continuous wave Doppler. In patients with clinical suspicion of dynamic LVOTO, further provocation maneuvers were conducted. LVOTO was defined as a maximal peak LVOT gradient ≥30 mmHg. Parameters quantifying systolic motion of the mitral valve were measured in parasternal and apical views, both at early and late systole, by an investigator blinded to individual patient characteristics. SAM was visually assessed and categorized into grade 0 (no SAM), I (leaflet motion towards LVOT), II (late systolic septal contact), and III (early systolic septal contact). Results We analyzed 142 patients (59±13 years, 42% women). LVOTO was present in 68 (48%) patients of whom 30 (21% of all) exhibited LVOTO at rest, and 38 (27% of all) had LVOTO only during provocation maneuvers (ie. dynamic LVOTO). SAM was present in 86 patients (60%) and had a sensivitiy, specificity and PPV of LVOTO of 91%, 69% and 73%, respectively (table). The late-systolic distance between mitral leaflet tip and anterior septum (TISls) measured in apical 3-chamber view was best associated with the degree of SAM (F=123, P&amp;lt;0.001), and with peak LVOT gradient (at rest: Pearson r=−0.817; during Valsalva maneuver: r=−0.816, both P&amp;lt;0.001). In ROC analyses (figure), the AUC of TISls for identification of LVOTO and dynamic LVOTO were 0.914 (95% CI 0.868–0.959) and 0.857 (0.786–0.927), respectively. TISls ≤14 mm had a 97% sensitivity for LVOTO and of 94% for dynamic LVOTO. TISls ≤9 mm showed specificity and PPV of 95% and 92% for LVOTO, and 94% and 83% for dynamic LVOTO, respectively. Conclusions Quantification of SAM by TISls showed high diagnostic accuracy in identifying HCM patients with LVOTO. Prospective studies are needed to assess the incremental benefit of this novel parameter in the diagnostic work-up of HCM patients. Funding Acknowledgement Type of funding sources: None.

Mitral valve abnormalities in decedents of sudden cardiac death due to hypertrophic cardiomyopathy and idiopathic left ventricular hypertrophy.

Mitral valve abnormalities in decedents of sudden cardiac death due to hypertrophic cardiomyopathy and idiopathic left ventricular hypertrophy.

Left Ventricular Outflow Tract Obstruction in Patients Treated With Milrinone for Cerebral Vasospasm: Case Report and Literature Review.

Subarachnoid hemorrhage is associated with high morbidity and mortality, and cerebral arterial vasospasm is one of its main complications that determines neurological prognosis. The use of intravenous milrinone is becoming more common in the treatment of vasospasm. This molecule has positive inotropic and vasodilating properties by inhibiting phosphodiesterase-3. Its most described side effects are cardiac arrhythmias and arterial hypotension. In this paper, we raise a new issue concerning milrinone and discuss an undescribed side effect of this treatment, left ventricular outflow tract obstruction (LVOTO). Dynamic LVOTO is a clinical situation favored by hypovolemia, decreased left ventricular afterload, and excessive inotropism that can lead to severe hemodynamic failure and pulmonary edema. To our knowledge, this is the first study describing milrinone-induced LVOTO. This could compromise cerebral perfusion and therefore the neurological prognosis of patients. While it is known that catecholamines may induce LVOTO, milrinone-induced LVOTO appears to be a new pathophysiological entity of which neurosurgical intensivists should be aware.

Major Clinical Issues in Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is one of the most common inheritable cardiomyopathies. Contemporary management strategies, including the advent of implantable cardioverter-defibrillators and effective anticoagulation, have substantially improved the clinical course of HCM patients; however, the disease burden of HCM is still high in Korea. Sudden cardiac death (SCD), atrial fibrillation and thromboembolic risk, dynamic left ventricular outflow tract (LVOT) obstruction, and heart failure (HF) progression remain important issues in HCM. SCD in HCM can be effectively prevented with implantable cardioverter-defibrillators. However, appropriate patient selection is important for primary prevention, and the 5-year SCD risk score and the presence of major SCD risk factors should be considered. Anticoagulation should be initiated in all HCM patients with atrial fibrillation regardless of the CHA2DS2-VASc score, and non-vitamin K antagonist oral anticoagulants are the first option. Symptomatic dynamic LVOT obstruction is first treated medically with negative inotropes, and if symptoms persist, septal reduction therapy is considered. The recently approved myosin inhibitor mavacamten is promising. HF in HCM is usually related to diastolic dysfunction, while about 5% of HCM patients show reduced left ventricular ejection fraction <50%, also referred to as "end-stage" HCM. Myocardial fibrosis plays an important role in the progression to advanced HF in patients with HCM. Patients who do not respond to guideline-directed medical therapy can be considered for heart transplantation. The development of imaging techniques, such as myocardial deformation on echocardiography and late gadolinium enhancement on cardiac magnetic resonance, can provide better risk evaluation and decision-making for management strategies in HCM.

Left Ventricular Hypertrophy and Hypertrophic Cardiomyopathy in Adult Solid Organ Transplant Recipients.

Background.Hypertrophic cardiomyopathy (HCM) in pediatric solid organ transplant recipients has been reported in association with use of calcineurin inhibitors. However, data on the incidence and prevalence of HCM in adult posttransplant patients are limited. We sought to describe the clinical characteristics of solid organ transplant recipients who were diagnosed with HCM from 2011 to 2021 at a single center.Methods.Patients who had undergone solid organ transplant and exhibited left ventricular hypertrophy with left ventricular wall thickness ≥13 mm on transthoracic echocardiography were included. Clinical history, pedigree analysis, clinical genetic testing, transthoracic echocardiography, cardiac magnetic resonance imaging, treatment, and follow-up testing results were collected. Categorical variables were described as n (%). Continuous variables were described with medians and interquartile ranges and compared using the Wilcoxon rank-sum and Kruskal-Wallis tests. A 2-sided P < 0.05 was considered statistically significant.Results.Three lung, 5 kidney, and 4 liver transplant recipients from 12 different families were included. Seven patients (58%) did not carry a preexisting diagnosis of hypertension, and none had a history of aortic or subaortic stenosis. A majority of patients exhibited asymmetric septal hypertrophy (67%; medial septal thickness versus left ventricular posterior wall thickness 17 versus 13 mm; P < 0.001) and dynamic left ventricular outflow tract (LVOT) obstruction (58%). All patients were managed long term with calcineurin inhibitors. Clinical genetic testing in 6 patients identified 2 with disease-causing variants in 2 sarcomere genes, myosin binding protein-C and myosin heavy chain 7. Four patients (33%) underwent successful septal reduction therapy for treatment of symptomatic LVOT obstruction.Conclusions.Symptomatic HCM with dynamic LVOT obstruction can develop in solid organ transplant recipients, and genetic testing can identify individuals with sarcomeric HCM. Medical management and septal reduction therapies are treatment options for severe symptomatic disease.

Impaired cardiopulmonary test performance as a marker of early functional impairment in patients with Anderson-Fabry disease

Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disease characterized by progressive glicosphingolipid accumulation in multiple organs, due to α-galactosidase a deficiency [1]. It is considered a rare disease although newborn genetic screening showed non-negligible prevalence (∼1:3.900) [1]. Cardiac manifestations include progressive Left Ventricular (LV) Hypertrophy (LVH), which may be extreme and provoke both reduced stroke volume and dynamic LV outflow tract obstruction [2-6].

The Feline Cardiomyopathies: 2. Hypertrophic cardiomyopathy.

Practical relevance:Hypertrophic cardiomyopathy (HCM) is the most common form of feline cardiomyopathy observed clinically and may affect up to approximately 15% of the domestic cat population, primarily as a subclinical disease. Fortunately, severe HCM, leading to heart failure or arterial thromboembolism (ATE), only occurs in a small proportion of these cats.Patient group:Domestic cats of any age from 3 months upward, of either sex and of any breed, can be affected. A higher prevalence in male and domestic shorthair cats has been reported.Diagnostics:Subclinical feline HCM may or may not produce a heart murmur or gallop sound. Substantial left atrial enlargement can often be identified radiographically in cats with severe HCM. Biomarkers should not be relied on solely to diagnose the disease. While severe feline HCM can usually be diagnosed via echocardiography alone, feline HCM with mild to moderate left ventricular (LV) wall thickening is a diagnosis of exclusion, which means there is no definitive test for HCM in these cats and so other disorders that can cause mild to moderate LV wall thickening (eg, hyperthyroidism, systemic hypertension, acromegaly, dehydration) need to be ruled out.Key findings:While a genetic cause of HCM has been identified in two breeds and is suspected in another, for most cats the cause is unknown. Systolic anterior motion of the mitral valve (SAM) is the most common cause of dynamic left ventricular outflow tract obstruction (DLVOTO) and, in turn, the most common cause of a heart murmur with feline HCM. While severe DLVOTO is probably clinically significant and so should be treated, lesser degrees probably are not. Furthermore, since SAM can likely be induced in most cats with HCM, the distinction between HCM without obstruction and HCM with obstruction (HOCM) is of limited importance in cats. Diastolic dysfunction, and its consequences of abnormally increased atrial pressure leading to signs of heart failure, and sluggish atrial blood flow leading to ATE, is the primary abnormality that causes clinical signs and death in affected cats. Treatment (eg, loop diuretics) is aimed at controlling heart failure. Preventive treatment (eg, antithrombotic drugs) is aimed at reducing the risk of complications (eg, ATE).Conclusions:Most cats with HCM show no overt clinical signs and live a normal or near-normal life despite this disease. However, a substantial minority of cats develop overt clinical signs referable to heart failure or ATE that require treatment. For most cats with clinical signs caused by HCM, the long-term prognosis is poor to grave despite therapy.Areas of uncertainty:Genetic mutations (variants) that cause HCM have been identified in a few breeds, but, despite valiant efforts, the cause of HCM in the vast majority of cats remains unknown. No treatment currently exists that reverses or even slows the cardiomyopathic process in HCM, again despite valiant efforts. The search goes on.

Dynamic thromboembolic left ventricular outflow tract obstruction after aggressive procoagulant treatment in hemorrhagic shock: a case report

BackgroundIn cases of hypertrophic obstructive cardiomyopathy (HOCM), the systolic anterior motion of the mitral valve apparatus results in an obstruction of the left ventricular outflow tract (LVOT), which is known as the SAM [systolic anterior motion] phenomenon. Hypothetically, a pathological obstruction of the LVOT of a different etiology would result in a comparable hemodynamic instability, which would be refractory to inotrope therapy, and may be detectable through echocardiography.Case presentationWe observed a severely impaired left ventricular function due to a combination of a thrombotic LVOT obstruction and distinctive mitral regurgitation in a 56-year-old Caucasian, female patient after massive transfusion with aggressive procoagulant therapy. Initially, the patient had to be resuscitated due to cardiac arrest after a long-distance flight. The resuscitation attempts in combination with lysis therapy due to suspected pulmonary artery embolism were initially successful but resulted in traumatic liver injury, hemorrhagic shock and subsequent acute respiratory distress syndrome (ARDS). Oxygenation was stabilized with veno-venous extracorporeal membrane oxygenation (ECMO), but the hemodynamic situation deteriorated further. Transesophageal echocardiography (TEE) showed a massive, dynamic LVOT obstruction. Two thrombi were attached to the anterior leaflet of the mitral valve, resulting in a predominantly systolic obstruction. Unfortunately, the patient died of multiple-organ failure despite another round of lysis therapy and escalation of the ECMO circuit to a veno-venoarterial cannulation for hemodynamic support.ConclusionMassive transfusion with aggressive procoagulant therapy resulted in mitral valve leaflet thrombosis with dynamic, predominantly systolic LVOT obstruction, comparable to the SAM phenomenon. The pathology was only detectable with a TEE investigation.

Exercise Echocardiography following Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy.

To investigate outcome after septal myectomy and to evaluate long-term hemodynamics with exercise echocardiography. This study included 40 consecutive patients operated with septal myectomy for hypertrophic obstructive cardiomyopathy from January 1998 to August 2017 at Skane University Hospital, Lund, Sweden. Perioperative clinical data and echocardiography measurements were reviewed retrospectively. Patients (n = 36) who were alive and living in Sweden were invited for exercise echocardiography to evaluate exercise capacity and hemodynamics, of whom 19 patients performed exercise echocardiography. Overall survival was 100% at 1 year and 96% at 5 years following surgery. Preoperative median resting peak LVOT (left ventricular outflow tract) gradient was 80 mm Hg. Septum thickness was reduced from 22 ± 4 mm preoperatively to 16 ± 3 mm postoperatively (p < 0.001). During exercise echocardiography, the peak LVOT gradient was 8 mm Hg at rest, and increased to 13 mm Hg during exercise echocardiography (p = 0.002). None of the patients had dynamic LVOT obstruction during exercise echocardiography, and there was no clinically significant systolic anterior motion or severe mitral insufficiency during exercise. Long-term survival following septal myectomy is very good. At long-term follow-up, LVOT gradients were low and exercise echocardiography demonstrated good hemodynamics.

Abstract 13876: Squat-to-stand Provocation of Dynamic Left Ventricular Outflow Tract Obstruction in Hypertrophic Cardiomyopathy

Background: Left ventricular outflow tract (LVOT) obstruction is an important determinant in management of hypertrophic cardiomyopathy (HCM). Valsalva maneuver and amyl nitrite are used in clinical practice during resting echocardiography to induce latent obstruction (LVOT gradient &lt;30 mmHg at rest, ≥30 mmHg with maneuver). With a nationwide shortage of amyl nitrite in 2019, we implemented a “repetitive squat-to-stand” maneuver to provoke LVOT obstruction during echocardiography. Methods: Patients with known or suspected HCM without resting obstruction who underwent repetitive squat-to-stand maneuver during echocardiography between February and September 2019 were included. Maximal instantaneous gradients were recorded. Provocable gradients were compared utilizing a two-sided t-test. Amyl nitrite was not available during the study period. Results: Squat-to-stand assessments were available in 125 patients without resting obstruction (age 58 ± 15 years, 67% male); 114 also performed Valsalva maneuver. 47 of 125 patients (37.6%) demonstrated provocable obstruction. 46 (36.8%) demonstrated latent obstruction provoked by squat-to-stand, which was severe (gradient ≥50 mmHg) in 29 (23.2%). Of the 46 patients, 19 demonstrated latent obstruction only with squat-to-stand but not with Valsalva, 13 of which demonstrated severe obstruction. Among patients with latent obstruction who performed both Valsalva and squat-to-stand maneuver (n=41), squat-to-stand resulted in a higher gradient than Valsalva maneuver (p&lt;0.0001, Figure). Conclusion: Repetitive squat-to-stand maneuver is a clinically useful adjunct to the traditional echocardiographic exam in HCM. This maneuver appears to be more sensitive than the Valsalva maneuver for identifying severe dynamic LVOT obstruction. Use of repetitive squat-to-stand warrants further study in comparison to amyl nitrite, particularly regarding cost savings and diagnostic performance.

Examining the impact of inducible ischemia on myocardial fibrosis and exercise capacity in hypertrophic cardiomyopathy

Myocardial ischemia in hypertrophic cardiomyopathy (HCM) is associated with poor outcomes. Vasodilator stress cardiac magnetic resonance (CMR) can detect and quantitate inducible ischemia in HCM patients. We hypothesized that myocardial ischemia assessed by CMR is associated with myocardial fibrosis and reduced exercise capacity in HCM. In 105 consecutive HCM patients, we performed quantitative assessment of left ventricular volume and mass, wall thickness, segmental wall thickening percent, segmental late Gadolinium enhancement (LGE), and extracellular volume fraction (ECV). Time-signal intensity curves of first pass perfusion sequences were generated for each segment at stress and rest. A myocardial perfusion reserve index (MPRI) (stress/rest slope) was calculated. Patients who underwent an echocardiographic (n = 73) and cardiopulmonary exercise test (n = 37) within 30 days were included. The mean age was 53.2 ± 15.4 years; 60% were male, and 82 patients had asymmetric hypertrophy. Segments with end diastolic thickness ≥ 1.2 cm had a higher burden of LGE (4.1% vs 0.5% per segment), reduced MPRI (2.6 ± 1.5 vs 3.1 ± 1.8) and reduced thickening percent (48.9 ± 41.7% vs. 105.3 ± 59.5%), (P < 0.0001 for all comparisons). Patients with ischemia (any segment with MPRI < 2) were more likely to have dynamic left ventricular outflow tract (LVOT) obstruction (63.3% vs 36.7%, P = 0.01), to be smokers (17% vs 6.9%, P = 0.04), and had a higher ECV (30% vs 28%, P = 0.04). The total LGE burden was similar between the two groups (P = 0.47). Increasing ischemia burden (number of segments with MPRI < 2) was associated with worsened ventilatory efficiency (VE/VCO2) (P < 0.001) but not peak oxygen consumption or anerobic threshold (P > 0.2). In a patient-level multivariable logistic regression model, only LVOT obstruction remained a significant predictor of ischemia burden (P = 0.03). Myocardial ischemia by CMR is associated with myocardial segmental dysfunction and interstitial fibrosis, as assessed by ECV, in HCM patients, even in segments free of LGE. Conversely, quantitative ischemia burden was not associated with replacement fibrosis as assessed by total LGE burden. Patients with ischemia had greater prevalence of dynamic LVOT obstruction; and in a subset of patients with cardiopulmonary exercise testing, ischemia burden was associated with worsened ventilatory efficiency.

Impact of preanaesthetic echocardiography on the planned anaesthetic management of cats

ObjectiveTo assess the impact of preanaesthetic echocardiography on the subsequent intended anaesthetic management plan in cats with incidental clinical findings that may indicate cardiac disease. Study designClinical study involving cats undergoing echocardiography and subsequent anaesthesia. AnimalsA total of 40 client-owned cats. MethodsEchocardiography was performed in conscious cats and the information was used to plan anaesthesia or sedation. An information sheet including relevant history, temperament, body condition score, clinical examination findings, current medication and results of any relevant tests such as haematology, biochemistry or Doppler blood pressure measurement was sent to three specialist anaesthetists and virtual case management plans were designed for each cat in two steps: step 1) anaesthetists were unaware of echocardiography results; and step 2) anaesthetists were aware of echocardiography results. In the second step the anaesthetists documented any changes to their original management plan, as either ‘step-up’ or ‘step-down’. ResultsOf the 40 cats, 26 had murmurs, four had a gallop rhythm, four had both findings and six had other findings. Pathology of potential haemodynamic significance was found on echocardiography in 23 cats, 17 of which anaesthetists had correctly identified as having disease before echocardiography. A proportion of cats with murmurs were subsequently deemed to have no significant pathology after echocardiography. Echocardiography findings in these cases were: dynamic left ventricular outflow tract obstruction (DLVOTO) without hypertrophy; DLVOTO without hypertrophy + dynamic right ventricular outflow tract obstruction (DRVOTO); DRVOTO; valvular dysplasia; normal. In a median of 26/40 (range 16–38) of cases, the anaesthetic plan was changed after provision of further information; in 15/40 (8–20) cases, this was a ‘step-up’ in care and in eight/40 (6–23) it was a ‘step-down’ in care. In cases with atrial enlargement (left atrium to aortic ratio of >1.6) and deemed at risk of cardiac failure, alpha-2 agonist use changed considerably with availability of echocardiography findings. Conclusionand clinical relevance Where there are abnormal cardiac findings on clinical examination in cats, echocardiography is required to accurately assess anaesthetic risk . The availability of echocardiographic information positively influences anaesthetic management.

Unusual case of combined aortic root replacement and repair of hypertrophic obstructive cardiomyopathy

Hypertrophic obstructive cardiomyopathy (HOCM) in association with aortic disease is uncommon. However, left ventricular outflow tract obstruction (LVOTO) generates turbulent flow patterns that could augment the aneurysmal change in the aortic root in cases of connective tissue disorder.1 Phenotypic heterogeneity in HOCM cases requires a tailored approach to correct all factors contributing to the dynamic LVOTO including the mitral valve and its subvalvular apparatus.2